Over recent years, with the development of digital processing technology, print images represented by photographic images and posters have been also able to be produced using an ink-jet apparatus or an electrophotographic image forming apparatus, in addition to the conventional silver halide photographic method and the conventional printing method such as gravure printing. In printed matter such as photographic images and posters produced using such an image forming apparatus, those finished by forming a uniform glossy surface over the entire image support area are demanded in some cases.
As a technique to form a uniform glossy surface over the entire image support area, there is a technique to form a glossy surface using, for example, a toner having no colorant component referred to as a clear toner or a transparent toner. Specifically, a clear toner is fed in a layered manner onto an image support in which image formation has been carried out using a toner or an ink-jet printer, followed by heating and cooling to form a glossy surface having uniform glossiness over the entire image support area (for example, refer to Patent Document 1). In this manner, formation of a uniform glossy surface over the entire image support area has become one of the effective methods to enhance the added value of printed matter.
In the above technique to form a uniform glossy surface (hereinafter referred to also as a clear toner layer) on an image support using a clear toner, a device referred to as a glossy surface forming device is used. In this device, an image is formed using an image forming apparatus such as a printer and then an image support to which a clear toner has been fed is heated to melt the clear toner. Then, via the melted clear toner, the image support is brought into close contact with a belt member. Subsequently, the image support is cooled in the state of being in close contact with the belt member to cure the clear toner. The thus-cured clear toner is peeled from the belt member to form a glossy surface on the image support (for example, refer to Patent Documents 2 and 3).
Incidentally, when a glossy surface is formed on an image support using a clear toner, air bubbles are occasionally accumulated in the interior of the glossy surface, whereby cloudiness of the glossy surface due to air bubble generation and occurrence of non-uniformity have become the causes of the decrease of image quality of formed printed matter. It has been thought that air bubble accumulation occurs since air present among toner particles or between an image support and a clear toner layer cannot be moved in the nip portion during fixing and then compressed. Therefor, a technique has been investigated in which on a clear toner, a member enabling to move air is provided and thereby air having been accumulated in the nip portion during fixing is moved to the outside to avoid occurrence of air bubble accumulation (for example, refer to Patent Document 4). This technique has been one to transfer a clear toner layer onto a fixing belt, in which such a transferred clear toner layer is provided with linear grooves in the direction parallel to or diagonally backward to the conveyance direction of the image support and then air having been accumulated the nip portion is discharged via the grooves.